SorbetAutoTyper

SorbetAutoTyper is a tool that is able to add sorbet signatures to files by instrumenting code, for example by running the test suite of a project.

Add this line to your application's Gemfile (you probably want to add it in the development/test section):

gem 'sorbet_auto_typer'

And then execute:

$ bundle

SorbetAutoTyper works in two steps:

1. Instrumentation
2. Analysis

The first step is to instrument the code. To be able to instrument even a large codebase, SorbetAutoTyper will stop instrumenting a method after a specific amount of calls. Underneath the hood the ruby TracePoint API is used to ensure maximum speed.

To instrument a codeblock, first configure the gem:

SorbetAutoTyper.configure do |c|
  c.output_file = File.join(Dir.pwd, 'tmp', "#{SecureRandom.uuid}.sig")
  c.filter_path = File.join(Dir.pwd, 'lib')
end

This will set up the gem to output a signature file with a random name to the tmp directory and only inspect files in the lib directory. This configuration only needs to be done once pr. process.

Next we can start and stop SorbetAutoTyper using SorbetAutoTyper.start! and SorbetAutoTyper.stop!.

Instrumenting a simple file could look like this:

SorbetAutoTyper.start!
a = MyModule::MyClass.new
a.hello
SorbetAutoTyper.stop!

In the context of a test runner like RSpec, the following could be added to the spec helper of the project:

SorbetAutoTyper.configure do |c|
  c.output_file = File.join(Dir.pwd, 'tmp', "#{SecureRandom.uuid}.sig")
  c.filter_path = File.join(Dir.pwd, 'lib')
end

RSpec.configure do |config|
  config.before(:suite) do
    SorbetAutoTyper.start!
  end

  config.after(:suite) do
    SorbetAutoTyper.stop!
  end
end

Running the analysis is as simple as running the sorbet-auto-typer tool within your project. If you run it without any arguments, it will print a bit of help:

$ bundle exec sorbet-auto-typer
Error: Please provide a SIGNATURE_FILE.

sorbet-auto-typer [OPTIONS] ... SIGNATURE_FILE

-h, --help:
   show help

--dry, -d:
   do not overwrite files, only display desired changes

--verbose, -v:
   more verbose output

SIGNATURE_FILE: Signature file to use for auto-generated types

The --dry and --verbose flags will make sure none of the source files are overwritten and provide a diff of the files. Those are recommended options on the first run.

When you are ready to run SorbetAutoTyper on your project, simply run it without any options and it will add method signatures to the source files in the project.

Bug reports and pull requests are welcome on GitHub at https://github.com/bss/sorbet_auto_typer. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

The gem is available as open source under the terms of the MIT License.

Everyone interacting in the SorbetAutoTyper project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.